The invention relates to a method for producing a fan wheel, in particular for a motor vehicle.
Due to the mechanical and thermal loads, axial-flow fans or ring fans for trucks are conventionally produced from PA6 (Nylon-6) with glass fibers as filler. One disadvantage of PA6 (Nylon-6) is that it absorbs water which brings with it a severe change in the mechanical characteristic values, i.e. the fan wheels always have to be designed with regard to the maximum water-absorption range. As a result, oversizing may occur. Furthermore, PA6 (Nylon-6) has a relatively high density, so the fan wheels are relatively heavy. This results, inter alia, in disadvantages (i) in the balancing quality and, (ii) in the driving mode, for the acceleration of the particular fan wheel. Fan wheels of this type are usually injection molded, for which purpose the casting compound is injected via a plurality of gate points.
FIG. 2 illustrates a conventional fan wheel 1 (jet ring fan). In order to produce the fan wheel, plastic is injected into the mold via a plurality of gate points. The plastic compound first fills the inner ring 3, then the fan wheel blades 2 and, finally, the outer ring. For optimized filling of the fan wheel blades 2, each fan wheel blade 2 is assigned a gate point. As a result, weld lines between the individual fan wheel blades 2 are produced on the inner ring 3 and on the outer ring.
A fan wheel produced by this known method leaves something to be desired, in particular with regard to the strength.